Canon AT 1 - Manual (Page 16)

Stopping-Down the Lens: Stopping-down
the lens can be performed by pushing the
stopped-down lever after setting the
aperture ring.
Power Source: One 6V silver oxide battery;
Eveready No. 544, UCAR No.544, JIS
4G13, and Mallory PX28. The battery
lasts the equivalent of 20,000 shutter
releases, or one year under normal use.
Battery Check: Battery power level can be
checked by the meter needle inside the
viewfinder -when the main switch is
turned to the battery check index mark
"C".
Flash Synchronization: X synchronization
is at 1/60 sec. M synchronization is at
1 /30 sec. and below.
Flash Terminal: The accessory shoe has a
direct flash contact and automatic flash
control contact. On the front of the
camera body is the flash terminal, JIS-B
type for flash units with a cord. It has a
built-in protective rim to prevent elect­
rical shock.
Automatic Flash: With the Canon Speedlite
1 55A, set the aperture to the prescribed